Method of making a solid dimer of alpha-methyl para-methyl styrene



Patented Dec. 30, 1947 METHOD OF MAKING A SbLID DIMEB F ALPHA-METHYLPARA-METHYL S Bernard H. Krese, New York, N. Y., nuignor to FederalTelephone and Radio Corporation,

New York, N. Y., a corporation of Delaware No Drawing. Application March13, 1945,

' Serial No. 582,578

Claims. (01. 260-469) This invention relates to a new dimer ofalphamethyl para-methyl styrene and its method of preparation. Dimericalpha-methyl para-methyl (AMPM) styrene is known in liquid form and thedesirability of producing this substance in a form which is solid undernormal working conditions has been recognized. Such a solid form isproduced in accordance with my invention and is a polymer which isdistinguished from formerly known comparable polymers in being a whitecrystalline solid. It is insoluble in water, either cold or hot, but hassubstantial solubility in many organic solvents. It is of utility bothalone as a coating material or may be compounded with other substancessuch as synthetic and natural resins, plastics and like materials toform compounds of varied utility.

The invention also comprehends the novel method by which the solid dimeris prepared. This method can be carried out at moderate temperatures andatmospheric pressure although an increase in pressure may result ingreater yields, less side-reactions and greater speed oi reaction.

To describe the invention in the method, reference is made to thefollowing outline of pre-- ferred procedure which is however merely anexemplification which might be modified within the scope of theinvention.

An important factor in the production of the solid dimer asdistinguished from the liquid dimer appears to reside in the temperatureat which the reaction takes place and the control of this temperature asthe reaction proceeds.

A suitable quantity of monomeric liquid alphamethyl para-methyl styrene(AMPM styrene, hereinafter referred to as "Monomer) is brought up to atleast 150C. in an oil bath. There is then added from two to ten percentby weight of a catalyst, for example, an activated diatomaceous earthsuch as fuller's earth and floridin. Suitable activation results fromheating fullers earth or the like in the air for approximately two hoursat from 300 to 350 C.

During the mixing and subsequently the material is stirred rapidly. Avigorous exothermic reaction ensues at atmospheric pressure and thetemperature will rise markedly unless controlled. It is desirable thatthe temperature reach 200 C. in order to carry out an efiicientproduction. However it should be kept at or below 250 C. to produce themaximum yield of the solid dimer.

The refraction index N may reach 1.5600 on completion of thedimerization and this may be used to measure the end point. However, theindex may not rise so high but reach a lower maximum despite continuedheating at 250 C. In this case the reaction is complete when the indexor the dimer no-longer rises.

After the reaction has ceased the liquified reaction mixture is filteredhot from the catalyst. The residue on cooling sets to a crystalline masswhich is then purified either by distillation or crystallization. Ayieldof from 90 to 95% is obtained. The product is a white crystallinesolid having a melting point of 40-41 C. and a molecular weight of-264corresponding to the formula Gaol-I24.

The dimer is insoluble in either hot or cold water. It is partiallysoluble in methanol and freely soluble in varying proportions in manycommon organic solvents including carbon tetrachloride, isopropanol,ethyl acetate, benzene,

hexane, cyclohexane, acetone, ether, dioxane, and

nitroethane.

Instead of starting with the monomer as outlined above, the solid dimermay be produced from the liquid form of dimer which is described andclaimed in the copending application of A. J. Werner et aL, filedDecember 21. 1943, Serial No. 515,168. This liquid dimer is formed inyields of from 70 to 95 percent by reaction with a catalyst such asactivated Iuller's earth, floridin and the like at temperatures notexceeding 200 C.

The liquid dimer, preferably isolated from impurities, is used in placeof the AMPM styrene to carry out the above described reaction. Otherdetails of the procedure are the same. It will be recognized that theconversion from'the liquid dimer to the solid dimer occurs when thetemperature of the former is raised above approximately 200 C. In otherwords, maintenance of the lower temperature, such as described in theabove mentioned application of Warner et al., results in the productionof the liquid dimer and a higher temperature accomplishes the conversioninto the solid dimer.

Accordingly the liquid dimer is used in carrying out the invention byreaction with a suitable catalyst. Here again from two to ten per centof a suitable catalyst, preferably an activated fullers earth such asactivated fioridin is added to the liquid dimer with vigorous stirring.The reaction ensues while a temperature of 200 to 300 C. is maintained.To prevent possible decomposition it is preferred to keep thetemperature below 250 C. The heating is continued for several hours, forexample from six to eight hours. At the conclusion of the reaction,determined as above indicated, a high yield, from to a quantitative 3100% is attained and the solid dimer separated and purified as indicatedabove.

The above description of the novel solid dimer and the preferred methodof its preparation has been set out by way of example only and the.invention is to be construed as limited only by the scope of thefollowing claims.

What I claim is:

1. The method of preparing solid dimeric alpha-methyl para-methylstyrene which comprises heating alpha-methyl para-methyl styrene ata'temperature within the range of 200 to 250 C. with stirring when mixedwith a clay-type catalyst.

2. The method of preparing solid dimeric alpha-methyl para-methylstyrene which comprises heating alpha-methyl para-methyl styrene at atemperature within the range of 200 to 250 C. with stirring when mixedwith a thermally activated diatomaceous earth.

3. The method of preparing solid dimeric alpha-methyl para-methylstyrene which comprises heating alpha-methyl para-methyl styrene at atemperature within the range of 200 to 250 C. with stirring when mixedwith a thermally activated fullers earth.

4. The method of preparing solid dimeric alpha-methyl para-methylstyrene which comprises heating alpha-methyl para-methyl styrene at atemperature within the range of 200 to 250 C. with stirring when mixedwith floridin.

5. The method of preparing solid dimeric alpha-methyl para-methylstyrene which comprises heating monomeric alpha-methyl paramethylstyrene at a temperature within the range of 200 to 250 C. with stirringwhen mixed with a thermally activated clay-type catalyst.

6. The method of preparing solid dimeric alpha-methyl para-methylstyrene which comprises heating liquid dimeric alpha-methyl para-methylstyrene at a temperature within the range of 200 to 250 C. with stirringwhen mixed with a thermally activated clay-type catalyst.

'7. The method of preparing solid dimeric alphat-methyl para-methylstyrene which comprises heating alpha-methyl para-methyl styrene at atemperature between 200 and 250 C. for several hours under atmosphericpressure while mixed with from two to ten percent of a thermallyactivated diatomaceous earth.

8. The method of preparing solid dimeric alpha-methyl para-methylstyrene which comprises heating alpha-methyl para-methyl styrene at atemperature between 200 and 250 C. for several hours under atmosphericpressure while mixed with from two-to ten percent of a thermallyactivated fuliers earth.

9. The method of preparing solid dimeric alpha-methyl para-methylstyrene which comprises heating alpha-methyl para-methyl styrene at atemperature between 200 and 250 C. for several hours under atmosphericpressure while mixed with from two to ten percent of a thermallyactivated floridin.

10. The method of preparing solid dimeric alpha-methyl para-methylstyrene which comprises heating alpha-methyl para-methyl styrene at atemperature between 200 and 250 C. for several hours under atmosphericpressure while mixed with from two to ten percent of a thermallyactivated diatomaceous earth, filtering while hot and purifying thefiltrate.

BERNARD H. KRESS.

REFERENCES CITED 6 (Copy in Division

